cpython/Lib/idlelib/rpc.py

# ASCII-art documentation
#
#  +---------------------------------+ +----------+
#  | SocketServer.BaseRequestHandler | | SocketIO |
#  +---------------------------------+ +----------+
#                  ^                      ^  ^
#                  |                      |  |
#                  | + -------------------+  |
#                  | |                       |
#  +-------------------------+        +-----------------+
#  | RPCHandler              |        | RPCClient       |
#  |-------------------------|        |-----------------|
#  | register()              |        | remotecall()    |
#  | unregister()            |        | register()      | 
#  |                         |        | unregister()    |
#  |                         |        | get_remote_proxy|
#  +-------------------------+        +-----------------+
#
import sys 
import socket
import select
import SocketServer
import struct
import cPickle as pickle
import threading
import traceback
import copy_reg
import types
import marshal

def unpickle_code(ms):
    co = marshal.loads(ms)
    assert isinstance(co, types.CodeType)
    return co

def pickle_code(co):
    assert isinstance(co, types.CodeType)
    ms = marshal.dumps(co)
    return unpickle_code, (ms,)

def unpickle_function(ms):
    return ms

def pickle_function(fn):
    assert isinstance(fn, type.FunctionType)
    return `fn`
 
copy_reg.pickle(types.CodeType, pickle_code, unpickle_code)
copy_reg.pickle(types.FunctionType, pickle_function, unpickle_function)

BUFSIZE = 8*1024

class RPCServer(SocketServer.TCPServer):

    def __init__(self, addr, handlerclass=None):
        if handlerclass is None:
            handlerclass = RPCHandler
# XXX KBK 25Jun02 Not used in Idlefork, see register/unregister note below.
#        self.objtable = objecttable 
        SocketServer.TCPServer.__init__(self, addr, handlerclass)

    # XXX KBK 25Jun02 Following method is not used (yet)
#      def verify_request(self, request, client_address):
#          host, port = client_address
#          if host != "127.0.0.1":
#              print "Disallowed host:", host
#              return 0
#          else:
#              return 1

# XXX KBK 25Jun02 The handlerclass is expected to provide register/unregister
#                 methods.  In Idle, RPCServer is instantiated with
#                 handlerclass MyHandler, which in turn inherits the
#                 register/unregister methods from the mix-in class SocketIO.
#                 It is true that this is asymmetric with the RPCClient's use
#                 of register/unregister, but I guess that's how a SocketServer
#                 is supposed to work.

#                 Exactly how this gets set up is convoluted.  When the
#                 TCPServer is instantiated, it creates an instance of
#                 run.MyHandler and calls its handle() method.  handle()
#                 instantiates a run.Executive, passing it a reference to the
#                 MyHandler object.  That reference is saved as an attribute of
#                 the Executive instance.  The Executive methods have access to
#                 the reference and can pass it on to entities that they
#                 command (e.g. RemoteDebugger.Debugger.start_debugger()).  The
#                 latter, in turn, can call MyHandler(SocketIO)
#                 register/unregister methods via the reference to register and
#                 unregister themselves.  Whew.

    # The following two methods are not currently used in Idlefork.
#      def register(self, oid, object):
#          self.objtable[oid] = object

#      def unregister(self, oid):
#          try:
#              del self.objtable[oid]
#          except KeyError:
#              pass


objecttable = {}

class SocketIO:

    debugging = 0

    def __init__(self, sock, objtable=None, debugging=None):
        self.mainthread = threading.currentThread()
        if debugging is not None:
            self.debugging = debugging
        self.sock = sock
        if objtable is None:
            objtable = objecttable
        self.objtable = objtable
        self.statelock = threading.Lock()
        self.responses = {}
        self.cvars = {}

    def close(self):
        sock = self.sock
        self.sock = None
        if sock is not None:
            sock.close()

    def debug(self, *args):
        if not self.debugging:
            return
        s = str(threading.currentThread().getName())
        for a in args:
            s = s + " " + str(a)
        s = s + "\n"
        sys.__stderr__.write(s)

    def register(self, oid, object):
        self.objtable[oid] = object

    def unregister(self, oid):
        try:
            del self.objtable[oid]
        except KeyError:
            pass

    def localcall(self, request):
        self.debug("localcall:", request) 
        try:
            how, (oid, methodname, args, kwargs) = request
        except TypeError:
            return ("ERROR", "Bad request format")
        assert how == "call"
        if not self.objtable.has_key(oid):
            return ("ERROR", "Unknown object id: %s" % `oid`)
        obj = self.objtable[oid]
        if methodname == "__methods__":
            methods = {}
            _getmethods(obj, methods)
            return ("OK", methods)
        if methodname == "__attributes__":
            attributes = {}
            _getattributes(obj, attributes)
            return ("OK", attributes)
        if not hasattr(obj, methodname):
            return ("ERROR", "Unsupported method name: %s" % `methodname`)
        method = getattr(obj, methodname)
        try:
            ret = method(*args, **kwargs)
            if isinstance(ret, RemoteObject):
                ret = remoteref(ret)
            return ("OK", ret)
        except:
            ##traceback.print_exc(file=sys.__stderr__)
            typ, val, tb = info = sys.exc_info()
            sys.last_type, sys.last_value, sys.last_traceback = info
            if isinstance(typ, type(Exception)):
                # Class exceptions
                mod = typ.__module__
                name = typ.__name__
                if issubclass(typ, Exception):
                    args = val.args
                else:
                    args = (str(val),)
            else:
                # String exceptions
                mod = None
                name = typ
                args = (str(val),)
            tb = traceback.extract_tb(tb)
            return ("EXCEPTION", (mod, name, args, tb))

    def remotecall(self, oid, methodname, args, kwargs):
        self.debug("remotecall:", oid, methodname, args, kwargs) 
        seq = self.asynccall(oid, methodname, args, kwargs)
        return self.asyncreturn(seq)

    def asynccall(self, oid, methodname, args, kwargs):
        request = ("call", (oid, methodname, args, kwargs))
        seq = self.putrequest(request)
        return seq

    def asyncreturn(self, seq):
        response = self.getresponse(seq)
        return self.decoderesponse(response)

    def decoderesponse(self, response):
        how, what = response
        if how == "OK":
            return what
        if how == "EXCEPTION":
            mod, name, args, tb = what
            self.traceback = tb
            if mod:
                try:
                    __import__(mod)
                    module = sys.modules[mod]
                except ImportError:
                    pass
                else:
                    try:
                        cls = getattr(module, name)
                    except AttributeError:
                        pass
                    else:
                        raise getattr(__import__(mod), name)(*args)
            raise name, args
        if how == "ERROR":
            raise RuntimeError, what
        raise SystemError, (how, what)

    def mainloop(self):
        try:
            self.getresponse(None)
        except EOFError:
            pass

    def getresponse(self, myseq):
        response = self._getresponse(myseq)
        if response is not None:
            how, what = response
            if how == "OK":
                response = how, self._proxify(what)
        return response

    def _proxify(self, obj):
        if isinstance(obj, RemoteProxy):
            return RPCProxy(self, obj.oid)
        if isinstance(obj, types.ListType):
            return map(self._proxify, obj)
        # XXX Check for other types -- not currently needed
        return obj

    def _getresponse(self, myseq):
        if threading.currentThread() is self.mainthread:
            # Main thread: does all reading of requests and responses
            while 1:
                response = self.pollresponse(myseq, None)
                if response is not None:
                    return response
        else:
            # Auxiliary thread: wait for notification from main thread
            cvar = threading.Condition(self.statelock)
            self.statelock.acquire()
            self.cvars[myseq] = cvar
            while not self.responses.has_key(myseq):
                cvar.wait()
            response = self.responses[myseq]
            del self.responses[myseq]
            del self.cvars[myseq]
            self.statelock.release()
            return response

    def putrequest(self, request):
        seq = self.newseq()
        self.putmessage((seq, request))
        return seq

    nextseq = 0

    def newseq(self):
        self.nextseq = seq = self.nextseq + 2
        return seq

    def putmessage(self, message):
        try:
            s = pickle.dumps(message)
        except:
            print >>sys.__stderr__, "Cannot pickle:", `message`
            raise
        s = struct.pack("<i", len(s)) + s
        while len(s) > 0:
            n = self.sock.send(s)
            s = s[n:]

    def ioready(self, wait=0.0):
        r, w, x = select.select([self.sock.fileno()], [], [], wait)
        return len(r)

    buffer = ""
    bufneed = 4
    bufstate = 0 # meaning: 0 => reading count; 1 => reading data

    def pollpacket(self, wait=0.0):
        self._stage0()
        if len(self.buffer) < self.bufneed:
            if not self.ioready(wait):
                return None
            try:
                s = self.sock.recv(BUFSIZE)
            except socket.error:
                raise EOFError
            if len(s) == 0:
                raise EOFError
            self.buffer += s
            self._stage0()
        return self._stage1()

    def _stage0(self):
        if self.bufstate == 0 and len(self.buffer) >= 4:
            s = self.buffer[:4]
            self.buffer = self.buffer[4:]
            self.bufneed = struct.unpack("<i", s)[0]
            self.bufstate = 1

    def _stage1(self):
        if self.bufstate == 1 and len(self.buffer) >= self.bufneed:
            packet = self.buffer[:self.bufneed]
            self.buffer = self.buffer[self.bufneed:]
            self.bufneed = 4
            self.bufstate = 0
            return packet

    def pollmessage(self, wait=0.0):
        packet = self.pollpacket(wait)
        if packet is None:
            return None
        try:
            message = pickle.loads(packet)
        except:
            print >>sys.__stderr__, "-----------------------"
            print >>sys.__stderr__, "cannot unpickle packet:", `packet`
            traceback.print_stack(file=sys.__stderr__)
            print >>sys.__stderr__, "-----------------------"
            raise
        return message

    def pollresponse(self, myseq, wait=0.0):
        # Loop while there's no more buffered input or until specific response
        while 1:
            message = self.pollmessage(wait)
            if message is None:
                return None
            wait = 0.0
            seq, resq = message
            if resq[0] == "call":
                response = self.localcall(resq)
                self.putmessage((seq, response))
                continue
            elif seq == myseq:
                return resq
            else:
                self.statelock.acquire()
                self.responses[seq] = resq
                cv = self.cvars.get(seq)
                if cv is not None:
                    cv.notify()
                self.statelock.release()
                continue

class RemoteObject:
    # Token mix-in class
    pass

def remoteref(obj):
    oid = id(obj)
    objecttable[oid] = obj
    return RemoteProxy(oid)

class RemoteProxy:

    def __init__(self, oid):
        self.oid = oid

class RPCHandler(SocketServer.BaseRequestHandler, SocketIO):

    debugging = 0

    def __init__(self, sock, addr, svr):
        svr.current_handler = self ## cgt xxx
        SocketIO.__init__(self, sock)
        SocketServer.BaseRequestHandler.__init__(self, sock, addr, svr)

    def setup(self):
        SocketServer.BaseRequestHandler.setup(self)
        print >>sys.__stderr__, "Connection from", self.client_address

    def finish(self):
        print >>sys.__stderr__, "End connection from", self.client_address
        SocketServer.BaseRequestHandler.finish(self)

    def handle(self):
        self.mainloop()

    def get_remote_proxy(self, oid):
        return RPCProxy(self, oid)

class RPCClient(SocketIO):

    nextseq = 1 # Requests coming from the client are odd

    def __init__(self, address, family=socket.AF_INET, type=socket.SOCK_STREAM):
        sock = socket.socket(family, type)
        sock.connect(address)
        SocketIO.__init__(self, sock)

    def get_remote_proxy(self, oid):
        return RPCProxy(self, oid)

class RPCProxy:

    __methods = None
    __attributes = None

    def __init__(self, sockio, oid):
        self.sockio = sockio
        self.oid = oid

    def __getattr__(self, name):
        if self.__methods is None:
            self.__getmethods()
        if self.__methods.get(name):
            return MethodProxy(self.sockio, self.oid, name)
        if self.__attributes is None:
            self.__getattributes()
        if not self.__attributes.has_key(name):
            raise AttributeError, name
    __getattr__.DebuggerStepThrough=1

    def __getattributes(self):
        self.__attributes = self.sockio.remotecall(self.oid,
                                                "__attributes__", (), {})

    def __getmethods(self):
        self.__methods = self.sockio.remotecall(self.oid,
                                                "__methods__", (), {})

def _getmethods(obj, methods):
    # Helper to get a list of methods from an object
    # Adds names to dictionary argument 'methods'
    for name in dir(obj):
        attr = getattr(obj, name)
        if callable(attr):
            methods[name] = 1
    if type(obj) == types.InstanceType:
        _getmethods(obj.__class__, methods)
    if type(obj) == types.ClassType:
        for super in obj.__bases__:
            _getmethods(super, methods)

def _getattributes(obj, attributes):
    for name in dir(obj):
        attr = getattr(obj, name)
        if not callable(attr):
           attributes[name] = 1

class MethodProxy:

    def __init__(self, sockio, oid, name):
        self.sockio = sockio
        self.oid = oid
        self.name = name

    def __call__(self, *args, **kwargs):
        value = self.sockio.remotecall(self.oid, self.name, args, kwargs)
        return value

#
# Self Test
#

def testServer(addr):
    class RemotePerson:
        def __init__(self,name):
            self.name = name 
        def greet(self, name):
            print "(someone called greet)"
            print "Hello %s, I am %s." % (name, self.name)
            print
        def getName(self):
            print "(someone called getName)"
            print 
            return self.name
        def greet_this_guy(self, name):
            print "(someone called greet_this_guy)"
            print "About to greet %s ..." % name
            remote_guy = self.server.current_handler.get_remote_proxy(name)
            remote_guy.greet("Thomas Edison")
            print "Done."
            print
            
    person = RemotePerson("Thomas Edison")
    svr = RPCServer(addr)
    svr.register('thomas', person)
    person.server = svr # only required if callbacks are used

    # svr.serve_forever()
    svr.handle_request()  # process once only

def testClient(addr):

    #
    # demonstrates RPC Client
    #
    import time
    clt=RPCClient(addr)
    thomas = clt.get_remote_proxy("thomas")
    print "The remote person's name is ..."
    print thomas.getName()
    # print clt.remotecall("thomas", "getName", (), {})
    print
    time.sleep(1)
    print "Getting remote thomas to say hi..."
    thomas.greet("Alexander Bell")
    #clt.remotecall("thomas","greet",("Alexander Bell",), {})
    print "Done."
    print 
    time.sleep(2)
    
    # demonstrates remote server calling local instance
    class LocalPerson:
        def __init__(self,name):
            self.name = name 
        def greet(self, name):
            print "You've greeted me!"
        def getName(self):
            return self.name
    person = LocalPerson("Alexander Bell")
    clt.register("alexander",person)
    thomas.greet_this_guy("alexander")
    # clt.remotecall("thomas","greet_this_guy",("alexander",), {})

def test():
    addr=("localhost",8833)
    if len(sys.argv) == 2:
        if sys.argv[1]=='-server':
            testServer(addr)
            return
    testClient(addr)

if __name__ == '__main__':
    test()